System and method for routing power across multiple microgrids having DC and AC buses

ABSTRACT

Systems and methods are described herein for managing the operations of a plurality of microgrid modules. A microgrid module includes transformers and/or power converters necessary for modifying the input AC or DC power sources to meet the required characteristics of the output power. The microgrid module further comprises a control software module and a power router software module. The control software module receives data from sensors in the microgrid module and controls the flow of power with controllable elements. The power router software module controls the operation of the power router. The power router can detect changes in demand for power within the microgrid module or from other microgrid modules. The power router can adjust the flow of power between the microgrid modules in response to changes in the supply of power to the microgrid module and changes in the demand for power from the microgrid module.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application incorporates by reference in their entirety thefollowing co-owned U.S. patent application Ser. No. 12/760,647 filedApr. 15, 2010 entitled System and Method for a Controlled InterconnectedDC and AC Bus Microgrid, and application Ser. No. 12/760,654, now U.S.Pat. No. 8,164,217, filed Apr. 15, 2010 entitled System and Method forManagement of a DC and AC Bus Microgrid, both of which are being filedconcurrently with this application.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to microgrids for controllingsmall distributed energy resources (DERs). More specifically, thepresent invention relates to a system and method for routing powerbetween multiple microgrids with DC and AC inputs and outputs.

2. Description of Related Art

In general, microgrids are electric networks that are capable ofderiving power from a number of sources including the conventional powergrid, localized power generating capabilities and alternative powersources such as solar arrays and wind turbines. The microgrid canaggregate power from a number of sources, converting the differentformats of power derived from multiple and diverse sources to commonvoltage and frequency formats that can be subsequently distributed toone or a number of loads. In addition, the microgrid can maintain thereliability of power to one or a number of loads in the face of changingpower levels that are derived from the multiple and diverse sources. Amicrogrid can be coordinated to provide power from a variety of powersources and to provide power with greater reliability. For example, amicrogrid can provide an alternate source of power to a site when thereis an interruption in the power delivered by the conventional utilitypower grid. A microgrid also can provide an alternate source of power,such as power from a renewable energy source, when renewable energy ispreferred over power delivered by the conventional utility power grid.The power that the microgrid supplies to a site may be derived from avariety of sources including energy storage devices, alternative energysources such wind or solar power, or from burning conventional fossilfuels. A description of prior art microgrid configurations is found inthe whitepaper entitled “Characterization of Microgrids in the UnitedStates” prepared for Sandia National Laboratories by Resource DynamicsCorporation dated January 2005 and incorporated herein by reference inits entirety.

In general, there are prior patents and published patent applicationsdirected to various aspects of microgrids. For example, U.S. Pat. No.7,116,010 relates to the control of small distributed energy resources.U.S. Pat. No. 6,603,672 discloses a power converter system which allowsvarious types of power formats to be derived from a variety of sourcesand converted in a predetermined manner to supplement power for alocalized grid. U.S. Pat. No. 5,804,953 discloses a power converter forconverting AC shore power for shipboard use, which converts a variety ofshore voltages for shipboard use. U.S. Pat. No. 6,819,087 discloses adistributed resource stabilization control for microgrid applications.U.S. Pat. No. 6,778,414 relates to a distributed system and methodologyfor electrical power regulation, conditioning and distribution on anaircraft. U.S. Pat. No. 6,765,370 discloses a system and method forbi-directional power conversion in a portable device. U.S. PublishedPatent Application No. 2008/0143304 describes a system and method forcontrolling a microgrid. U.S. Patent Application No. 2005/0105306discloses a power converter that is adaptable for interfacing a varietyof power sources with a three-phase AC power grid. U.S. PatentApplication No. 2004/0124711 discloses a mobile power system housed in astandard freight container; the system distributes power in a pluralityof configurations such as different voltage. U.S. Patent Application No.2004/0061380 discloses a power management system for variable loadapplications. U.S. Patent Application No. 2002/0036430 discloses a localarea grid for distributed power.

The disclosures in these prior patents and published patent applicationsis hereby incorporated herein by reference in their entirety. However,as described further below, none of these prior patents or publishedpatent applications provides the solutions of the invention describedand claimed in this application.

SUMMARY OF THE INVENTION Summary of the Problem

The present state of the art for microgrid technology has severaldeficiencies, including the absence of a comprehensive system and methodfor managing the operation of a microgrid module capable of handling ACto AC, DC to DC, AC to DC, and DC to AC across multiple inputs andoutputs. There is a further need to be able to manage the operation ofmultiple microgrid modules that are coupled together. Absent from theprior art is a scalable system capable of managing multiple microgridmodules. Finally, there is a need for a system and method for managingmultiple microgrid modules that can respond to changes in poweravailability and loads by adjusting the flow of power supplied to and bythe multiple microgrid modules.

Thus there is a need for advances in the art of electrical microgridsand their management that addresses these deficiencies. Suchdeficiencies are overcome by the present invention, as is furtherdetailed below.

Summary of the Solution

The present invention addresses the foregoing limitations in theexisting art by providing a system and method for managing multiplemicrogrid modules that can each operate with AC to AC, DC to DC, AC toDC, and DC to AC across multiple inputs and outputs. The presentinvention comprises a power router element that can be installed in orcoupled to a microgrid module capable of sensing demand for power fromanother microgrid module and controlling the flow of power to and fromthe other microgrid module. The microgrid module comprises a microgridcomputer installed with control software modules to control theoperation of the microgrid module. Power router software modules used tocontrol the power router element can be installed on the microgridcomputer with the other control software modules, on the power routerelement, or on a separate computing device. The power router element,the power router software modules, and the control software modulessupport the management and sharing of power between multiple microgridmodules coupled together.

In a first exemplary embodiment, the invention comprises an apparatusfor managing a microgrid module comprising a microgrid computer coupledto the circuit layer of the microgrid module. The microgrid computer cancomprise a control software module and a power router software modulethat control the operation of the microgrid module. The microgrid modulecomprises a power router that can detect a demand for power from asecond microgrid module and communicate that demand to the power routersoftware module. The power router software module can compare the demandto rules controlling the operation of the microgrid module. If the rulespermit, the power router software module can direct the power router toincrease the power supplied by the microgrid module to the secondmicrogrid module. The power router of the microgrid module transmitspower to a second power router of the second microgrid module via aninter-microgrid connection. The power router can also comprise aboost/buck component for increasing or decreasing the voltage of powertransmitted on the inter-microgrid connection.

In another exemplary embodiment, the invention comprises a method forcontrolling the operation of a plurality of microgrid modules. Themethod comprises a power router of a first microgrid module detecting ademand for power from a second microgrid module. A power router softwaremodule can receive the demand and, if the demand satisfies one or morerules stored in computer-readable memory, the power router softwaremodule can authorize the power router to increase the power supplied tothe second microgrid module. The method further comprises a sensordetecting an interruption in the power supplied to the first microgridmodule. In such a situation, the power router can decrease the power thefirst microgrid supplies to the second microgrid module and increase thepower the first microgrid draws from the second microgrid.

In yet another exemplary embodiment, the invention comprises acomputer-readable memory comprising computer-executable instructions forexecution on a first microgrid computer of a first microgrid module. Thecomputer-readable memory can be installed on or coupled to the firstmicrogrid computer. The computer-executable instructions include firstprogram instructions for a control software module to receive power flowdata from the first microgrid module. The instructions further includesecond program instructions for receiving demand data indicating ademand for additional power from a second microgrid module. Thirdprogram instructions can analyze the demand data and authorize a powerrouter to increase the power supplied to the second microgrid module.The control software module can comprise fourth program instructions forreceiving interruption data indicating an interruption in power receivedby the first microgrid module and fifth program instructions fordetermining that insufficient power is being supplied to the firstmicrogrid module. Lastly, sixth program instructions can direct thepower router to increase the power drawn from the second microgridmodule to the first microgrid module.

These and other exemplary embodiments of the invention will be describedin greater detail in the following text and in the associated figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating an overview of components in accordancewith an exemplary embodiment of the invention.

FIG. 2 is a diagram illustrating an overview of components in accordancewith an exemplary embodiment of the invention.

FIG. 2A is a diagram illustrating the components of a computing devicein accordance with an exemplary embodiment of the invention.

FIG. 3 is a diagram illustrating an overview of the components of thephysical circuit layer in accordance with an exemplary embodiment of thepresent invention.

FIGS. 4A through 4D are diagrams illustrating portions of the componentsof the physical circuit layer in accordance with an exemplary embodimentof the present invention.

FIG. 5 is a diagram illustrating the connection of two microgrid modulesvia an inter-microgrid connection in accordance with an exemplaryembodiment of the invention.

FIG. 6 is a diagram illustrating the boost/buck components of powerrouter elements of two microgrid modules in accordance with anotherexemplary embodiment of the invention.

FIG. 7 is a diagram illustrating the connection of multiple microgridmodules in accordance with an exemplary embodiment of the presentinvention.

FIG. 8 is a diagram illustrating the components of an exemplary powerrouter element of a microgrid module using a bi-directional boost/buckcontroller in accordance with an exemplary embodiment of the presentinvention.

FIG. 9 is a diagram illustrating the components of an exemplary powerrouter element of a microgrid module using a back-to-back three-phaseswitching bridges in accordance with an exemplary embodiment of thepresent invention.

FIG. 10 is a diagram illustrating a serial configuration of a pluralityof microgrid modules in accordance with an exemplary embodiment of thepresent invention.

FIG. 11 is a diagram illustrating a ring configuration of a plurality ofmicrogrid modules in accordance with an exemplary embodiment of thepresent invention.

FIG. 12 is a diagram illustrating a star point configuration of aplurality of microgrid modules in accordance with an exemplaryembodiment of the present invention.

FIG. 13 is a diagram illustrating a fan-out configuration of a pluralityof microgrid modules in accordance with an exemplary embodiment of thepresent invention.

FIG. 14 is a diagram illustrating a central star configuration of aplurality of microgrid modules in accordance with an exemplaryembodiment of the present invention.

FIG. 15 is a flow chart diagram illustrating a process for managing theoperation of a plurality of microgrid modules coupled together inaccordance with an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The present invention comprises a portable microgrid module that isfully integrated, that can manage both AC and DC inputs and AC and DCoutputs, and that can manage power sharing with one or more othermicrogrid modules. The microgrid module comprises a power router elementthat can detect a demand for power either from the microgrid module orfrom another microgrid module and can route power to or from themicrogrid module. The power router element can comprise a processor andassociated software modules that can communicate with software modulesinstalled on a microgrid computer of the microgrid module. A powerrouter software module can be installed on the power router element, onthe microgrid computer, or on a separate computing device. The powerrouter software module can make decisions concerning the routing ofpower to or from the microgrid module based on the power available tothe microgrid module and the load demands on the microgrid module. Inalternative embodiments of the invention, the power router softwaremodule can be installed in the power router element. The power routerelement also has the capability to increase or decrease the voltage ofthe power it sends and receives in order to conform to the needs of theparticular load. For situations where the microgrid module istransmitting power over a significant distance to a second microgridmodule, the power router can convert DC power to AC power for thetransmission.

The microgrid module comprises a circuit layer comprising AC and DCbuses, sensors, controllable elements, and converters. The microgridcomputer further comprises a control software module, a power managementmodule, and memory for storing rules associated with the operation ofthe microgrid module. The microgrid module also can include or becoupled to energy storage devices such as batteries and capacitors. Theintegrated control of the connection of multiple DC and AC buses withinthe microgrid module allows for deterministic real-time control overbi-directional power sources from intermittent and continuous renewableand conventional power sources. Real-time control over the distributedpower sources supplying the microgrid module allows the microgrid moduleto respond to interruptions in one power supply and to transition toanother power supply.

The microgrid module of the present invention can accept alternative,renewable, and conventional power inputs into both DC and AC buses anddistributes or converts them as appropriate to match standardized busvalues across the input, load, macrogrid, and microgrid to microgridbuses. The microgrid module can provide power conversion from DC to DC,AC to AC, AC to DC and DC to AC between the buses under dynamic localcontrol. The microgrid of the present invention also has the capacity tostore electrical energy or energy in a form transmutable into electricalenergy, such as in a chemical form, for later distribution.

Each microgrid module can comprise various sub-systems and devices thatinclude, but are not limited to, quick-connect/quick-disconnect bus barsand plates, step-up and step-down transformers, patch orinter-connection panels and intelligent breakers and sensors, batteries,ultra-capacitors, flywheels, and other temporary or permanent energystorage devices and systems and their control electronics. The microgridmodule can also include power converters, circuitry to accommodate phaseimbalance by providing the appropriate neutral connections, and variousphysical wiring and physical mounting capabilities to provide foradequate stabilization and insulation of the various components in themodular microgrid system.

As referenced above, installed on the microgrid module's computer are apower management software module and a control software module. Thepower management software module can retrieve one or more businessparameters stored in a computer-readable memory and convert the one ormore business parameters to rules for operating the microgrid module.The power management software module can store the rules in a localcomputer-readable memory typically located in the microgrid module'scomputer. The control software module receives data from sensors locatedin the physical circuitry layer of the microgrid module. The controlsoftware module can apply the rules stored in the localcomputer-readable memory to the data received from the sensors todetermine which commands to send to the physical circuitry layer. Thecontrol software module sends commands to controllable elements locatedin the physical circuitry layer to control the operation of themicrogrid module.

Turning to the figures, in which like numerals indicate like elementsthroughout the figures, exemplary embodiments of the present inventionare illustrated and will be described in the following text. Those ofskill in the art will appreciate that the following are merelynon-limiting preferred embodiments and alternate embodiments can beimplemented in accordance with the invention.

Referring to FIG. 1, an exemplary architecture for a microgrid module 5can be depicted in three layers. The first layer is the physicalcircuitry layer 10. The physical circuitry layer comprises the AC and DCinput and output buses, the sensors and controllable elements thatmonitor and control the flow of power into and out of the microgridmodule, and other conventional electrical components such as convertersand transformers. The sensors and controllable elements that monitor andcontrol the microgrid module can vary from simple sensors and switchesto more complex “intelligent” sensors and switches that can includetheir own software and processing capabilities. Exemplary, non-limitingembodiments of the physical circuitry layer 10 are depicted in greaterdetail in FIG. 3, FIGS. 4A-4D and in the related application entitled“System and Method for a Controlled Integrated DC and AC Bus Microgrid”filed concurrently with this application.

The intermediate layer of the architecture for the microgrid is thecontrol software layer 15 and the final layer is the rules managementlayer 20 which includes business, regulatory and safety rules. Thecontrol software layer 15 is typically installed on a local computingdevice and can be implemented in, for example, active messagequeuing/message broker software as is known to those of ordinary skillin the art. While the control software layer is typically installed on alocal computing device, those of ordinary skill in the field willunderstand that software modules controlling the microgrid module or itscomponents can be installed in components of the physical circuit layeror in other computing devices coupled to the microgrid module. Thecontrol software layer 15 can also comprise a power router softwaremodule that controls a power router element located in the physicalcircuitry layer 10. The rules management layer 20 also is typicallyinstalled on a local computing device and can be implemented in, forexample, a virtual machine with a service oriented architecture and useSOAP (Simple Object Access Protocol) as a messaging protocol. The rulesmanagement layer 20 comprises the power management software modulereferenced above and described in greater detail in the following text.

Referring to FIG. 2, another exemplary architecture diagram illustratesin further detail the components of an exemplary microgrid module. FIG.2 shows the physical circuit layer 205 comprising sensors 210 andcontrollable elements 215. The sensors 210 can collect data from the ACand DC buses (not shown in FIG. 2) and deliver the collected data to themicrogrid computer 220. The sensors 210 can detect a variety of powerconditions including direction, voltage, current and power levels, andassociated changes and the rate of change of these parameters. Forexample, the sensors can provide data indicating a demand for power,data indicating the flow of power within the microgrid module, and dataindicating an interruption in the flow of power to the microgrid module.The controllable elements 215 can include switches, power converters,and other intelligent electrical devices to control the flow of power toand from the microgrid module. Intelligent electrical devices typicallyinclude their own software and processing capabilities. The controllableelements 215 can receive commands from the control software module 225of the microgrid computer 220. In certain embodiments, intelligentcontrollable elements can perform control functions withoutcommunicating with a separate microgrid computer. As discussed ingreater detail in connection with FIGS. 4D and 6-9, the physicalcircuitry layer can also comprise or be coupled to a bus interfacecontroller which is also referred to as a power router. The power routerwill be described in greater detail in the text associated with FIGS. 4Dand 6-9.

The microgrid computer 220 provides a single or multiple user interfaceto the various controllable microgrid elements. The microgrid computer220 communicates with the sensors 210 and controllable elements 215 ofthe physical circuit layer. The microgrid computer 220 comprisesinstalled power management software module 228 and control softwaremodule 225. The power management software module 228 can retrievebusiness parameters from computer memory such as remote memory device238. The power management software module converts the businessparameters into rules that the control software module 225 can apply tothe operation of a microgrid module. The control software module 225uses the rules to process data received from the sensors 210 andgenerate commands for sending to the controllable elements 215.

The microgrid computer 220 can also comprise power router softwaremodule 230 that controls the flow of power to and from the microgridmodule and other microgrid modules via a power router located in thephysical circuitry layer 205 (not shown in FIG. 2). For example, asdescribed further in connection with FIGS. 10-14, multiple microgridmodules can be coupled in various arrangements and share power. Thepower router software module 230 can be implemented to access the rulesstored in memory 235 so that the rules govern decisions for routingpower to and from the microgrid module. In certain embodiments, thepower router software module can be installed directly in the powerrouter element located in the physical circuitry layer, instead of beinginstalled separately in the microgrid computer 220. In one embodiment,the power router software module can control the operation of themicrogrid module on which it is installed. In other embodiments of theinvention, the power router software module can operate in a centralizedarrangement so that it controls the operation of several microgridmodules. In a centralized arrangement, the power router software modulemay be installed on a separate computing device distinct from themicrogrid computer where the separate computing device is coupled toeach of the several microgrid modules it controls.

Where there are multiple microgrid modules, one or more power routerscan control the operation of the microgrid modules. Communication ofcontrol commands or other data between the multiple microgrid modulescan take place via a communications network, for example, using InternetProtocol. Alternatively, communications between the multiple microgridmodules also can take place over power transmission lines, such as theinter-microgrid connections described in connection with FIGS. 5 through14. For example, packets of information can be transmitted on powertransmission lines along with the AC or DC power transmitted along thoselines. In such an embodiment, the packets of information can compriseelectrical power routing information, as well as other control commands.

The microgrid computer 220 also can comprise local data storage 235 andcan be coupled to remote data storage 238. The remote storage device 238can store business parameters, sensor data, and log data. The businessparameters can be defined by the operator of the microgrid and mayrepresent a variety of “real world” parameters. As one example, thebusiness parameters can represent the costs of power from theconventional AC power grid and from alternate power sources coupled tothe microgrid. In another example, the business parameters can representexpected load demands and preferences for certain power sources. Thesensor data that can be stored at the remote data storage device 238 isthe data the control software module 225 receives from the sensors 210.The sensor data stored at the remote data storage device 238 can alsocomprise data the power router software module 230 receives from thepower router. The power management software module 228 can access thissensor data to adjust the rules based on the operation of the microgridmodule. The remote storage device 238 can also store log data describingthe operation of the microgrid module over time that can be used forfurther planning and operation of the microgrid module.

In the preferred embodiment, the local data storage 235 stores the rulescreated by the power management software module 228 from the businessparameters. The control software module 225 uses the rules to controlthe controllable elements 215. Similarly, the power router softwaremodule 230 can access the rules to control the power router. Locallystoring the rules assists the control software module 225 and the powerrouter software module 230 to respond quickly to changes in powersupplied to the microgrid module. For example, the rules can define whenthe microgrid module will draw power from a power storage device, fromthe conventional utility grid, or from another microgrid module. Moregenerally, the rules can control various operating modes for themicrogrid module including islanding, peak shaving, power conditioning,aggregate load reduction, and the sale of power back to a utility. Inalternate embodiments of the invention, software modules and datastorage devices can be located either locally or remotely in differentarrangements of computing environments.

Although the exemplary embodiments herein are generally described in thecontext of software modules running on a computing device local to thephysical circuitry layer as in FIG. 2, those skilled in the art willrecognize that the present invention also can be implemented inconjunction with other program modules in other types of computingenvironments. Furthermore, those skilled in the art will recognize thatthe present invention may be implemented in a stand-alone or in adistributed computing environment. In a distributed computingenvironment, program modules may be physically located in differentlocal and remote memory storage devices. Execution of the programmodules may occur locally in a stand-alone manner or remotely in aclient/server manner. Examples of such distributed computingenvironments include local area networks of an office, enterprise-widecomputer networks, and the global Internet.

The detailed description of the exemplary embodiments includes processesand symbolic representations of operations by conventional computercomponents, including processing units, memory storage devices, displaydevices and input devices. These processes and symbolic representationsare the means used by those skilled in the art of computer programmingand computer construction to most effectively convey teachings anddiscoveries to others skilled in the art. These processes and operationsmay utilize conventional computer components in a distributed computingenvironment, including remote file servers, remote computer servers, andremote memory storage devices. Each of these conventional distributedcomputing components is accessible by a processing unit via acommunications network.

The present invention includes computer hardware and software whichembody the functions described herein and illustrated in the appendedflow charts. However, it should be apparent that there could be manydifferent ways of implementing the invention in computer programming,and the invention should not be construed as limited to any one set ofcomputer program instructions. Further, a skilled programmer would beable to write such a computer program to implement the disclosedinvention without difficulty based on the flow charts and associateddescription in the application text, for example. Therefore, disclosureof a particular set of program code instructions is not considerednecessary for an adequate understanding of how to make and use theinvention. The inventive functionality of the claimed computer hardwareand software will be explained in more detail in the followingdescription in conjunction with the other figures in the application.

Referring now to FIG. 2A, aspects of an exemplary computing environmentin which the present invention can operate are illustrated. Thoseskilled in the art will appreciate that FIG. 2A and the associateddiscussion are intended to provide a brief, general description of thepreferred computer hardware and program modules, and that additionalinformation is readily available in the appropriate programming manuals,user's guides, and similar publications.

FIG. 2A illustrates a conventional computing device 120 suitable forsupporting the operation of the preferred embodiment of the presentinvention such as the microgrid computer. As illustrated previously inFIG. 2, the microgrid computer 220 typically comprises multiple softwaremodules. While not required for the computing device implemented in amicrogrid module, the computing device 120 illustrated in FIG. 2Aoperates in a networked environment with logical connections to one ormore remote computers 111. The logical connections between computingdevice 120 and remote computer 111 are represented by a local areanetwork 173 and a wide area network 152. Those of ordinary skill in theart will recognize that in this client/server configuration, the remotecomputer 111 may function as a file server or computer server.

The computing device 120 includes a processing unit 121, such as“PENTIUM” microprocessors manufactured by Intel Corporation of SantaClara, Calif. The computing device 120 also includes system memory 122,including read only memory (ROM) 124 and random access memory (RAM) 125,which is connected to the processor 121 by a system bus 123. Thepreferred computing device 120 utilizes a BIOS 126, which is stored inROM 124. Those skilled in the art will recognize that the BIOS 126 is aset of basic routines that helps to transfer information betweenelements within the computing device 120. Those skilled in the art willalso appreciate that the present invention may be implemented oncomputers having other architectures, such as computers that do not usea BIOS, and those that utilize other microprocessors.

Within the computing device 120, a local hard disk drive 127 isconnected to the system bus 123 via a hard disk drive interface 132. Afloppy disk drive 128, which is used to read or write a floppy disk 129,is connected to the system bus 123 via a floppy disk drive interface133. A CD-ROM or DVD drive 130, which is used to read a CD-ROM or DVDdisk 131, is connected to the system bus 123 via a CD-ROM or DVDinterface 134. A user enters commands and information into the computingdevice 120 by using input devices, such as a keyboard 140 and/orpointing device, such as a mouse 142, which are connected to the systembus 123 via a serial port interface 146. Other types of pointing devices(not shown in FIG. 2A) include track pads, track balls, pens, headtrackers, data gloves and other devices suitable for positioning acursor on a computer monitor 147. The monitor 147 or other kind ofdisplay device is connected to the system bus 123 via a video adapter148.

The remote computer 111 in this networked environment is connected to aremote memory storage device 150. This remote memory storage device 150is typically a large capacity device such as a hard disk drive, CD-ROMor DVD drive, magneto-optical drive or the like. Those skilled in theart will understand that software modules are provided to the remotecomputer 111 via computer-readable media. The computing device 120 isconnected to the remote computer by a network interface 153, which isused to communicate over the local area network 173.

In an alternative embodiment, the computing device 120 is also connectedto the remote computer 111 by a modem 154, which is used to communicateover the wide area network 152, such as the Internet. The modem 154 isconnected to the system bus 123 via the serial port interface 146. Themodem 154 also can be connected to the public switched telephone network(PSTN) or community antenna television (CATV) network. Althoughillustrated in FIG. 2A as external to the computing device 120, those ofordinary skill in the art can recognize that the modem 154 may also beinternal to the computing device 120, thus communicating directly viathe system bus 123. Connection to the remote computer 111 via both thelocal area network 173 and the wide area network 152 is not required,but merely illustrates alternative methods of providing a communicationpath between the computing device 120 and the remote computer 111.

Although other internal components of the computing device 120 are notshown, those of ordinary skill in the art will appreciate that suchcomponents and the interconnection between them are well known.Accordingly, additional details concerning the internal construction ofthe computing device 120 need not be disclosed in connection with thepresent invention.

Those skilled in the art will understand that program modules, such asan operating system 135 and other software modules 160 a, 163 a and 166a, and data are provided to the computing device 120 viacomputer-readable media. In the preferred computing device, thecomputer-readable media include the local or remote memory storagedevices, which may include the local hard disk drive 132, floppy disk129, CD-ROM or DVD 131, RAM 125, ROM 124, and the remote memory storagedevice 150.

Referring to FIG. 3, an exemplary microgrid module 300 is shown. Asillustrated, the microgrid module 300 may operate from a variety ofpower sources, including a connection to the local utility grid 320 andone or more distributed energy resources (“DERs”) 310 such as internalcombustion engine/generator sets, microturbine generators, fuel cells,wind turbines, and photovoltaic arrays. In addition, the microgridnetwork may have to level the power demands of various loads against theavailable power sources using energy storage assets 330 which mayinclude batteries (as shown), flywheels, electrochemical capacitorsand/or superconducting magnetic energy storage components (SMES).

Although the microgrid module 300 is labeled as a 250 kVA module, thatvalue is merely an example and other microgrid modules within the scopeof this invention can be designed to handle smaller or larger amounts ofpower. The microgrid module may have to provide power to several loadsystems with a variety of power format requirements including 208 V-3phase, 480 V-3 phase, 120 V-single phase, 48 VDC, and 300 VDC asexamples. As illustrated in FIG. 3, the microgrid module 300 includesone or more AC output buses that supplies power to one or more AC loads340. Exemplary microgrid module 300 also includes a DC output bus 350supplying power to a DC load. Processing power to flow from varioussources to various load and energy storage assets and from energystorage assets to the loads requires the use of power conversion tointerface various incoming and outgoing power formats.

The exemplary embodiments set forth in FIGS. 4A-4D illustrate in greaterdetail the components of the microgrid module 300 shown in FIG. 3. FIGS.4A-4D are broken up into four more detailed components of the overviewshown in FIG. 3. Those of skill in the art will recognize that theembodiments shown in FIGS. 4A-4D may be modified by adding, removing, orrearranging conventional electrical components without departing fromthe scope of the invention.

Turning to FIG. 4A, DERs 310 are illustrated as connected to DC inputbus 420. As illustrated in FIG. 4A, the microgrid module may compriseone or more DC input buses 420 and may be coupled to one or more DERs310. As explained previously, the DERs 310 can be one or more of avariety of energy sources, including conventional and renewable energysources. If the DER 310 is an AC power source, a converter 415 can beused to convert the AC power to DC power for transmission onto the DCinput bus 420. The DC input bus 420 can also be coupled to a DCdiagnostic element 417. The DC diagnostic element 417 can comprise oneor more sensors that can communicate with the control software module225.

FIG. 4A also illustrates an exemplary AC grid connection 320 thatconnects to the AC grid input bus 409 of the microgrid module. Theconnection with the AC grid allows power from the conventional utilitygrid to be fed to the microgrid module. In certain embodiments atransformer 405 will be necessary to adjust the voltage of the powerflowing from the utility grid to the microgrid module. An AC diagnosticmodule 407 can also be located at the AC grid connection 320. The ACdiagnostic module can comprise one or more sensors in communication withthe control software module 225. The AC diagnostic module 407 canprovide data to the control software module 225 about the flow of powerfrom the utility grid to the microgrid module and the control softwaremodule 225 can control the power flow at this connection with one ormore controllable elements in the physical circuitry layer. The AC gridinput bus also can be coupled to converter 411 for converting AC powerto DC power that flows to the DC input bus 420. The DC input busreceiving power from the AC grid input bus 409 can also comprise anotherDC diagnostic element 413.

FIG. 4A also illustrates exemplary elements for disconnecting themicrogrid module from the AC grid. For example, disconnect switch 403and grid fusing 404 can be used to disconnect the microgrid module fromthe AC grid. In one embodiment, the disconnect switch 403 can becontrolled by the control software module 225 or be activated by aperson when it is necessary to disconnect the microgrid module from theAC grid. Grid fusing 404 can be implemented as an added safety measurecapable of disconnecting the microgrid module from the AC grid in theevent of a dangerous situation. Although not illustrated in FIGS. 3 and4A-4D, similar disconnect switches and fuses can be implemented at otherpoints where the microgrid module connects to power sources, loads orother microgrid modules. These disconnect switches and fuses can beimplemented to allow the control software module, the power routersoftware module, or a person to quickly disconnect the microgrid modulewhen necessary.

Referring to the exemplary illustration in FIG. 4B, one can see thatconnections A, B, C, and D from FIG. 4A have corresponding connectionpoints A, B, C, and D in FIG. 4B. These connection points at A, B, C,and D do not represent physical elements of the microgrid module, butmerely illustrate the connection points between FIGS. 4A and 4B. FIGS.4C and 4D have a similar arrangement and FIGS. 4A-4D are intended toprovide a more detailed illustration of the overview of the exemplaryembodiment shown in FIG. 3.

In FIG. 4B, the DC input bus 420 has two primary connections. First, theDC input bus 420 can be coupled to a DC output bus 350 for supplying DCpower from the microgrid module. The DC input bus 420 and DC output bus350 may be linked through a power converter (not shown in FIG. 4B) ifneeded to adjust the input and output voltages. While the embodimentdescribed in connection with FIGS. 4A through 4D includes a DC input busand a DC output bus, those of skill in the art will recognize that twodistinct DC buses are not required. For example, other microgrid modulesmay comprise a single DC bus that receives DC power at one point anddelivers DC power at another point.

Second, the DC input bus can feed one or more converters 435 implementedto convert DC power to AC power for distribution on the AC output bus446. The AC output bus 446 is coupled to the AC grid input bus 409 and atransformer 440 can be placed between the AC grid input bus 409 and theAC output bus 446 if needed to adjust the input and output voltages. Asillustrated in exemplary FIG. 4B, an AC diagnostic element 430 can beplaced between converter 435 and the AC output bus 446. The ACdiagnostic element 430 can comprise one or more sensors allowing thecontrol software module 225 to monitor and control the operation of thephysical circuit layer of the microgrid module.

FIG. 4B includes connection points E and F to the elements of FIG. 4C.Exemplary FIG. 4C shows additional components of the exemplary microgridmodule including internal ultra-capacitor 442 and internal battery 444.In alternate embodiments, the internal energy storage components shownin FIG. 4C may not be internal parts of the microgrid module but may beexternal and coupled to the microgrid module. For example, as shown inFIG. 4C, the DC output bus 350 (not shown in FIG. 4C) may be coupled toan external battery via connection 446. The energy storage devices shownin FIG. 4C are coupled to the DC output bus 350 via converters 439 and448. These converters function to convert the DC voltage levelassociated with the energy storage elements with the voltage level ofthe DC output bus 350. Specifically, the voltage level associated witheach energy storage device may be substantially different from that ofthe DC bus. Moreover, the voltage levels associated with each energystorage device may vary substantially depending on the state-of-chargeof the energy storage device. In general, as an energy storage device ischarged, its associated voltage increases. Similarly, in general, as anenergy storage device is discharged while delivering energy to themicrogrid module, the associated voltage decreases. Power converters 439and 448 can adjust voltage levels so that the voltage level of the DCoutput bus 350 and the energy storage devices is consistent.

The energy storage devices also are coupled to one or more DC diagnosticelements 436, 433 and 450. As with other diagnostic elements previouslydiscussed, the DC diagnostic elements 436, 433 and 450 can comprise oneor more sensors in communication with the control software module 225.The energy storage devices illustrated in FIG. 4C are merelyrepresentative and those of skill in the art will appreciate that otherarrangements of energy storage devices can be placed either internal orexternal to the microgrid module and perform a similar function ofstoring energy provided by the microgrid module and subsequentlyproviding it back to the microgrid module as needed.

Referring to FIG. 4D, exemplary elements connected to points G and Hfrom FIG. 4B are illustrated. Point G shows the connection of the DCoutput bus 350 to a bus interface controller 455. The bus interfacecontroller 455 controls the flow of power between the microgrid moduleillustrated in FIGS. 4A-4D and one or more other microgrid modules. Asdescribed in further detail below, multiple microgrid modules can becoupled together and the bus interface controller (or power router) 455manages the flow of power between the coupled microgrid modules. Thepower router 455 typically comprises control and power convertercircuits that communicate with a software module such as the powerrouter software module 230 illustrated in FIG. 2. In certainembodiments, the power router 455 may not be part of the microgridmodule, but can be coupled to the microgrid module. Moreover, in certainembodiments the power router 455 can comprise its own power routersoftware module. One or more microgrid tie connections 459 connect theDC output bus 350 to other microgrid modules. The DC output bus can alsocomprise one or more DC diagnostic elements 464 and 457 which canperform sensing functions as described previously.

FIG. 4D also illustrates exemplary elements connected to the AC outputbus 446 at point H. One or more AC load connections 340 can be coupledto the AC output bus 446. The 3-phase AC load connection shown in FIG.4D is merely exemplary and a variety of AC loads having differentvoltages and phase combinations can be connected to the AC output bus446 of the microgrid module. The AC load connections can also compriseAC diagnostic elements similar to those described previously.

Those of skill in the art will recognize that the microgrid illustratedin FIGS. 3 and 4A-4D is merely exemplary and that other microgrids canbe designed in different arrangements within the scope of thisinvention. For example, in alternate embodiments of the invention, themicrogrid may comprise different distributed energy resources, differentpower converters and transformers, or the microgrid may not be connectedto the conventional utility power grid. Likewise, alternate embodimentsof the invention may not include energy storage devices or the energystorage devices may be only internal to the microgrid module. In otherembodiments, the microgrid computer can be implemented in a variety ofcomputing environments and can include other software such as the powerrouter software module. In yet other embodiments, the power routersoftware module can be installed on the power router or installed on aseparate computing device coupled to the microgrid module.

Referring to FIG. 5, microgrid A 505 and microgrid B 510 are showncoupled together by inter-microgrid connection 515 in accordance with anexemplary embodiment of the invention. Microgrid A 505 and microgrid B510 are simplified representations of microgrid modules and do notillustrate all of the components discussed previously in connection withFIGS. 4A-4D. As shown in FIG. 5, the inter-microgrid connection 515 istypically bidirectional in that it permits power flow to and from eithermicrogrid module. In the preferred embodiment, when the two microgridmodules are in operation, the microgrid module in need of power canreceive power from the other microgrid module. Either microgrid moduleis capable of providing power to or receiving power from the othermicrogrid module depending on the instantaneous power needs andavailabilities. The direction of power flow can be controlled in realtime and near-instantaneously by the power router software module whichcan be installed in the power router, on the microgrid computer, or on aseparate computing device coupled to the power router.

In the simplified representation of FIG. 5, the inter-microgridconnection is shown coupled to a bus in each microgrid. While not shownin FIG. 5, a power router, as shown in FIG. 4D, typically connects theDC bus of each microgrid module to the inter-microgrid connection.Furthermore, while not specified in FIG. 5, the bus can be either an ACbus or a DC bus, however, in the preferred embodiment theinter-microgrid connection is coupled to a DC bus in each microgridmodule.

Turning to FIG. 6, exemplary boost-buck components of the power routerare illustrated. Specifically, FIG. 6 shows boost-buck component 605 ofa power router (not shown) of microgrid module A and boost-buckcomponent 610 of a power router (not shown) of microgrid module B. FIG.6 also illustrates the inter-microgrid connection between the twoboost-buck components. In this exemplary embodiment, boost-buckcomponent 605 receives power from the DC bus of microgrid module A andincreases the voltage of the DC power before transmitting it on theinter-microgrid connection to microgrid module B. When boost-buckcomponent 610 receives DC power from microgrid module A, it decreasesthe voltage of the DC power before it is transmitted to the DC bus ofmicrogrid module B. Similarly, when DC power is transmitted frommicrogrid module B to microgrid module A, the voltage is increased byboost-buck component 610 and decreased by boost-buck component 605.Although the different microgrid modules may have different operatingconditions, the boost-buck component enables the different microgridmodules to share power. Therefore, if microgrid module A and microgridmodule B are operating at different voltages, the boost-buck componentscan be used to adjust the voltage of the power transmitted between themicrogrid modules.

Referring to FIG. 7, an exemplary embodiment of the invention isillustrated with multiple microgrid modules coupled via inter-microgridconnections or bus ties. In the exemplary embodiment shown in FIG. 7,each microgrid module 705, 710, and 715 comprises a bus interfacecontroller, or power router, with two connection points labeled BI1 andBI2. The two connection points enable each microgrid module to becoupled to two other microgrid modules, such as in the seriesconfiguration shown in FIG. 7. In other embodiments of the invention,the power router can comprise fewer or more connection points as neededto support the particular application. FIG. 7 also shows abi-directional arrow illustrating the communication of control andstatus information between the bus interface microgrid controller andthe power router software module (not shown).

Turning to FIG. 8, an exemplary boost-buck component 805 of an exemplarypower router is illustrated. As shown in FIG. 8, exemplary boost-buckcomponent 805 comprises two sides, side A controls power exported fromthe microgrid to the inter-microgrid bus and side B controls powerimported from the inter-microgrid bus to the microgrid. Side A comprisesa pulse-width modulator control 810, diodes 820 and 825, inductor 815,and capacitor 830. The components of side A are used to adjust thevoltage of the power exported to the inter-microgrid bus and, asdescribed previously, in the preferred embodiment the voltage of thepower is increased prior to exporting the power. Side B comprises apulse-width modulator control 835, diodes 840 and 845, and inductor 850.The components of side B are used to adjust the voltage of the powerimported from the inter-microgrid bus to the local bus of the microgridmodule and, as described previously, in the preferred embodiment thevoltage of the imported power is decreased by the boost buck component805.

The operation of Side A and Side B in exemplary component 805 is similarexcept each side controls the flow of power in opposite directions asdiscussed above. The detailed operation of each side is explained hereby considering the operation of Side A. Side A operates to export powerfrom the microgrid module to the inter-microgrid bus. Specifically, theDC voltage of the microgrid bus appears across the +/−terminals at theleft side of the diagram. The pulse width modulator control 810 causesthe binary switching of switching element 812. The switching element 812is switched in a manner which causes the build up of current in inductor815. Specifically, when switching element 812 is turned on, current issupplied from the microgrid and increases in inductor 815.

The level of current flowing in inductor 815 continues to increaseproportionally to the voltage difference between the input and outputterminals of the boost/buck circuit and continues to increase for aslong as switch element 812 is turned on. When the current on inductor815 reaches some desired level, switching element 812 is turned off andthe current increase ceases. Once the switching element 812 is turnedoff, current flowing in inductor 815 is directed through free-wheelingdiode 825. During the interval when switching element 812 is turned off,the current in the inductor continues to flow into the inter-microgridbus by virtue of the free-wheeling action of diode 825. As power isdelivered to the inter-microgrid bus, the current level flowing ininductor 815 decreases. Once the current level in inductor 815 reachessome minimum value, switching element 812 is once again turned on,essentially recharging the inductor 815 back to some maximum currentlevel required to maintain the appropriate average power flow from themicrogrid to the inter-migrogrid bus.

Generally, the switching element 812 is switched at a multi-kilohertzrate to effect precise control of the average current flow throughinductor 815. Specifically, the average current flowing through inductor815 is controlled by the pulse width modulation control circuit 810based upon the desired amount of power that is to be transferred fromthe microgrid to the inter-microgrid bus.

The operation of Side B of the interface controller is similar to thatof Side A with the exception that power in being imported from theinter-microgrid bus to the microgrid based upon the control of theaverage current that is flowing in inductor 815. The average currentflowing in inductor 815 is controlled by the switching action ofswitching element 837 which is controlled by pulsed width modulatorcontrol circuit 835.

The direction of the power flow (into or out of the microgrid) isdetermined by the power router software module and can be subject to avariety of factors including the instantaneous state of power demand,power delivered, and business rules.

FIG. 9 illustrates an alternative embodiment of a power router inaccordance with the present invention. The power router 905 illustratedin FIG. 9 is capable of converting DC power from the local DC bus of themicrogrid to AC power before transmitting the AC power on theinter-microgrid bus. Exemplary power router 905 is beneficial forapplications where the microgrid modules are separated by relativelylong distances (for example, on the order of hundreds of feet) and thepower must be transmitted over a long distance on the inter-microgridbus. In such situations, there may be a significant difference in the DCbus voltage levels of each of the microgrid modules. Moreover, differentmicrogrids may have been designed to operate with significantlydifferent DC bus voltages. In both of these situations, it may benecessary to provide additional voltage matching and/or voltagereference isolation capability than that provided by the bus interfacecontroller 805.

Exemplary power router 905 comprises pulse-width modulator controls 910and 915 separated by transformer 920, wherein the transformer 920comprises two back-to-back three-phase voltage source pulse widthconverters. The two converters are essentially mirror images of eachother, both capable of converting an AC, three-phase waveform to a DCvoltage (active rectification) or a DC voltage to an AC three-phasewaveform (inversion). Either converter can function in the AC to DC modeor DC to AC mode. However, when one converter operates in the DC to ACmode, the other converter will operate in the AC to DC mode. As such,the DC voltage from the microgrid can be converted to an AC three-phasewaveform and subsequently converted back to a DC voltage fortransmission of power onto the inter-microgrid bus. Conversely, the DCvoltage on the inter-microgrid bus can be converted to an AC three-phasewaveform and subsequently converted back to a DC voltage so that powercan be transferred to the microgrid module. Large differences in DCvoltages on the DC bus of the microgrid and the inter-microgrid bus canbe accommodated by the high-frequency transformer 920 that is interposedbetween the two converters.

The operation of the exemplary DC-AC-DC transformer can be described byconsidering the export of power from a microgrid onto theinter-microgrid bus. In this situation, the converter circuitry on theleft side of transformer 920 functions as an inverter, converting the DCvoltage supplied by the microgrid to an AC three-phase waveform. Thisconversion takes place by switching switch elements Q11-Q16 in a propersequence to provide a three-phase waveform to the primary of thehigh-frequency transformer 920. Pulse width modulation control circuit910 provides the signals to properly switch the switching elementsQ11-Q16 to provide the proper three-phase waveform to the primary of thehigh-frequency transformer 920. The converter circuitry on the rightside of high-frequency transformer 920 subsequently functions as anactive rectifier circuit which converts the three-phase waveform fromthe secondary of the high-frequency transformer 920. Activerectification occurs when switching elements Q21-Q26 are switched in theappropriate sequence to effect the rectification of the AC waveform atthe secondary of the high-frequency transformer 920. Pulse widthmodulation control circuit 915 provides signals to properly switch theswitching elements Q21-Q26 to achieve the active rectification function.

The operation of the power router 905 when power is being imported to amicrogrid module from the inter-microgrid bus is similar to thatexplained above with the exception that the converter circuitry on theright side of high-frequency transformer 920 functions as a DC to ACinverter and the converter circuitry on the left side of thehigh-frequency transformer 920 functions as the active rectifier. Theconverter circuitry on the left side of high frequency transformer 920functions as an active rectifier delivering power to the DC bus of themicrogrid module.

In exemplary power router 905, the direction of the power flow (into orout of the microgrid) is determined by the power router software moduleand can be subject to a variety of factors including the instantaneousstate of power demand, power delivered, and business rules.

FIGS. 10 through 14 illustrate different exemplary configurations ofmicrogrid modules. These configurations shown in FIGS. 10 through 14 aremerely exemplary and other configurations in different arrangements andwith more or fewer microgrid modules can be implemented to meetparticular needs for power. In the exemplary embodiment shown in FIG.10, four microgrid modules are connected in series via inter-microgridconnections or ties and DC power can be transmitted in both directionsbetween each microgrid module. FIG. 10 also shows an expanded view ofmicrogrid module #1 illustrating certain of the internal components ofthe exemplary microgrid module. The expanded view shown in FIG. 10 showsa bus interface controller or power router coupled to an internal DC buswithin the microgrid module. The expanded view also shows the powerrouter connected to the connection hub by contacts KDN-1 and KDN-2 whichcan be used to connect or disconnect the microgrid module to theinter-microgrid tie.

FIGS. 11 through 14 illustrate other exemplary configurations formultiple microgrid modules. These other arrangements employ componentssimilar to those described previously, but allow microgrid modules to becoupled to more than one other microgrid module. In configurationscomprising multiple microgrid modules, the microgrid modules can bearranged in different ways. For example, in some configurations, themultiple microgrid modules can be managed centrally by a power routersoftware module located on one microgrid module. In alternativeembodiments, each microgrid module can comprise its own power routersoftware module and can be managed locally.

Referring to FIG. 15, a method 1500 is illustrated describing theoperation of multiple microgrid modules coupled together in accordancewith one exemplary embodiment of the invention. Exemplary process 1500begins with microgrid module 1 receiving power on a DC input bus andsupplying power to an AC output bus in step 1505. As explained above,the microgrid modules can comprise components for converting DC power toAC power and vice versa. In step 1510, the power router detects a demandfor power from microgrid module 2 and sends the demand data to the powerrouter software module. In step 1515, the power router software modulecompares the received demand data to one or more rules governing theoperation of microgrid module 1. Assuming the rules are satisfied, thepower router software module directs the power router to increase thepower delivered from microgrid module 1 to microgrid module 2.Alternatively, if microgrid module 1 did not have power to spare, thedemand for additional power could be declined.

Referring to step 1520, a sensor in the circuitry layer of microgridmodule 1 detects an interruption in the power supplied to microgridmodule 1 on the DC input bus. In step 1525, the control software modulereceives data from the sensor and determines that insufficient power isbeing supplied to microgrid module 1. While steps 1520 and 1525, and theother steps illustrated in exemplary process 1500, are shown insequence, those skilled in the art will appreciate that certain stepscan occur in parallel or in a different sequence from that illustratedin process 1500. For example, the receipt of data from sensors at thecontrol software module in step 1520 and 1525 is a step that can occurat various times throughout process 1500.

Referring to step 1530, the power router software module analyzes therules and commands the power router to increase the power drawn frommicrogrid module 2. The actions of the power router software module canbe triggered by a command from the control software module.Alternatively, the power router software module can be implemented toperiodically or in real-time monitor the status of the microgrid moduleand control the power router accordingly. In response to theinsufficient power being supplied to microgrid module 1, in step 1535,the power router reduces the power that microgrid module 1 supplies tomicrogrid module 2 and increases the power supplied by microgrid module2 to microgrid module 1.

The steps in exemplary process 1500 are merely one example of theapplications for the power router software module and managing multiplemicrogrid modules. Those of skill in the art will appreciate that notall of the steps illustrated in process 1500 are required in order touse the microgrid module. Furthermore, the steps of process 1500 can beperformed in other sequences and other steps can be added for otherapplications of the microgrid module.

In conclusion, the invention, as described in the foregoing exemplaryembodiments, comprises multiple coupled microgrid modules that canreceive either AC or DC power from a variety of power sources and supplyeither AC or DC power to a load or storage device. Because the microgridmodules are coupled, they can also be managed to share power. A powerrouter at a first microgrid module can detect a demand for power from asecond microgrid module. A power router software module can decidewhether the first microgrid power will supply additional power to thesecond microgrid module in response to the demand. The power router canalso adjust the voltage or form of the power delivered to the secondmicrogrid module.

The embodiments set forth herein are intended to be exemplary. From thedescription of the exemplary embodiments, equivalents of the elementsshown herein and ways of constructing other embodiments of the inventionwill be apparent to practitioners of the art. For example, conventionalelectrical components can be added or modified within the microgrid butremain within the scope of the invention. Similarly, the methodsdescribed herein are merely exemplary and the power router softwaremodule can be designed in a variety of ways to control the operation ofone or more microgrid modules. Many other modifications, features andembodiments of the invention will become evident to those of skill inthe art. It should be appreciated, therefore, that many aspects of theinvention were described above by way of example only and are notintended as required or essential elements of the invention unlessexplicitly stated otherwise. Accordingly, it should be understood thatthe foregoing relates only to certain embodiments of the invention andthat numerous changes can be made therein without departing from thespirit and scope of the invention.

We claim:
 1. An apparatus for controlling the operations of a pluralityof microgrid modules comprising: a first microgrid module comprising afirst DC bus receiving power for the first microgrid module and a firstAC output bus supplying power to a load; a second microgrid modulecomprising a second DC bus receiving power for the second microgridmodule and a second AC output bus supplying power to a load; the firstmicrogrid module further comprising a first power router coupled to thefirst DC bus, the first power router supplying power to aninter-microgrid connection for delivery to the second microgrid module;the second microgrid module further comprising a second power routercoupled to the second DC bus, the second power router receiving powerfrom the inter-microgrid connection for supplying to the secondmicrogrid module, wherein at least one of the first power router and thesecond power router is capable of sensing demand for power from thesecond microgrid module.
 2. The apparatus of claim 1, wherein the firstpower router comprises a first power router software module controllingthe first power router.
 3. The apparatus of claim 1, wherein the firstmicrogrid module further comprises a circuit layer comprising a sensor;and a microgrid computer comprising a computer readable memorycomprising rules; a control software module receiving data from thesensor and commanding the power router software module to increase powerto be supplied from the second microgrid module to the first microgridmodule; a power router software module commanding the first power routerto decrease power transmitted to the second microgrid module and toincrease power drawn from the second microgrid module.
 4. The apparatusof claim 3, wherein the second power router is controlled by the powerrouter software module.
 5. The apparatus of claim 1, wherein the firstpower router can convert power transmitted on the inter-microgridconnection from DC power to AC power and back to DC power.
 6. Theapparatus of claim 1, wherein the power router comprises a boost/buckcomponent for increasing and decreasing the voltage of power transmittedon the inter-microgrid connection.